Rotary engine with cylinders of different design and volume

ABSTRACT

A rotary internal combustion engine including a housing structure defining a toroidal volume and including first and second housing sections, a rotor structure mounted for rotation in the housing structure and including first and second rotor members respectively that coact with first and second housing sections to define first and second toroidal cylinders. The intake and compression strokes are performed in the first toroidal cylinder and the resultant compressed charge being thereafter transferred by a transfer mechanism through a transfer passage to the second toroidal cylinder where combustion occurs and expansion and exhaust strokes are performed. In the device at least one of the following is true: the transfer mechanism is operative to maintain the volume of the charge substantially constant during the transfer operation; the first and second cylinders have disparate configurations; the second toroidal cylinder has a larger volume that the first toroidal cylinder with the transfer mechanism maintaining the volume of the charge substantially constant during the transfer operation irrespective of the larger volume of the second toroidal cylinder as compared to the first toroidal cylinder.

BACKGROUND

The present invention relates to internal combustion engines and in particular to internal combustion engines with coupled cylinders.

The basic principals of the four stroke-internal combustion engine may be equally applied to conventional reciprocating piston engines as well as rotary engines. In general, all four strokes of the cycle are performed within the same cylinder. That is, a single piston deployed within a cylinder travels through the series of intake compression combustion/expansion and exhaust strokes. Therefore, the power is generated in only one of four strokes, unlike two stroke engines in which power is generated in one of two strokes.

However, two stroke engines have historically been fuel inefficient due to the overlap of the exhaust and intake processes during a single stroke and the manner in which these processes occur.

With respect to rotary type engines, toroidal cylinder configurations have emerged in which piston elements travel on a continuous path through a single toroidal chamber. In an attempt to increase power, the number of pistons has been increased. This has been done in the past by increasing the number of pistons traveling through the same toroidal chamber. Alternatively, additional toroidal chambers have been added, which include additional pistons. This alternative is basically linking two or more separate engines.

In an effort to improve the basic efficiency of a rotary type engine, it has been proposed to configure first and second cylinders utilizing a common rotor deployed within a single toroidal chamber with all four strokes on the four stroke cycle being performed simultaneously with the intake and compression strokes performed in the first cylinder simultaneous to combustion and the expansion and exhaust strokes of a different cycle being performed in the second cylinder. Such a coupled cylinder engine, entitled Internal Combustion Engine with Coupled Cylinders, is disclosed in International Application Number PCT 1IL2005/000855 filed on 9 Aug. 2005 and published on Feb. 16, 2006 as International Publication Number WO 2006/01635882.

Whereas the coupled cylinder engine disclosed in the identified PCT application offers significant improvements in overall efficiency as compared to prior art rotary engines, applicant has conceived further efficiency improvements in the coupled engine design and these further improvements are the subject of the present application.

SUMMARY

The operations performed over four strokes of an engines operating cycle may be subdivided into stage 1 involving fuel charge preparation and stage 2 involving performance of work. Energy is consumed during the first part of the cycle while work is performed during the second part. The identified coupled cylinder application offers a procedure for performing these two parts of the cycle separately from each other in different toroidal cylinders of the same design. However, different stages of the operating cycle have specific features of their own. Thus, a high efficiency of the entire operating cycle can only be achieved with account being made for the specific operating conditions.

The present invention is based on the use of two different toroidal cylinder types, taking into account specifics of the first and the second stages of the operating cycle.

Type 1 cylinders will be adapted to accommodate, the operating sequence, as follows: filling the cylinder with incoming gas charge, charge compression, and bringing it to a ready to use state as per a preset ratio of compression.

Type 2 cylinders will be designed to allow for a ready to use fuel charge inlet with no changes in charge volume and pressure, charge ignition in this operating state, charge combustion and expansion to be followed by exhaust of combustion products.

To insure optimal operation of the Type 1 toroidal cylinder, and with the cylinders repeatedly filled by one charge portion after another and the charges being compressed along this propagation, a specific interior cylinder geometry will be applied, i.e., geometry intended to provide the least possible fuel charge flow resistance along the propagation path from the cylinder inlet to the place of ready to use charge collection to ready to ignite collection location and its size and geometry inside the cylinder will basically depend on the preset engines specific charge compression value and on conditions of the charge transfer for ignition. In transfer of the ready to ignite fuel charge mix, the charge volume shall remain unchanged.

The condition of maintaining, a constant fuel charge volume during the process of cylinder to cylinder transfer requires that upon volume reduction in the first cylinder, the volume will be increased by the same amount in the second cylinder. Provided the cylinders maintain similar geometry, this premise means that both the toroidal cylinders in question will feature equal charge inlet/outlet cross-section. In the present case when various purpose cylinders feature use various geometries, the condition of constant volume maintenance will be confined to satisfying the requirement when the charge inlet/outlet cross-section values are in inverse proportion to their respective lengths, i.e. to toroidal cylinder diameter values:

-   -   s/S=d/D where s/S are cross-sections of charge inlet/outlet and         d/D are diameters of respective toroidal cylinders.

The cylinder to cylinder charge transfer shall be capable of providing for charge transfer with the least possible losses. The charge inlet/outlet shall only be open for as long as the actual charge is being transferred, remaining shut throughout the rest of the cycle. Such charge transfer path shall demonstrate low hydraulic resistance, low intrinsic volume and total isolation of gaseous combustion products from the consecutive incoming fuel charge.

The geometry of Type 2 toroidal cylinders will be determined based on requirements for the best possible use of the fuel charge energy. The efficiency of the heat to work transformation process will be expressed using the ratio of:

-   -   J=1−t/T where T is the process commencement temperature and t is         the process termination temperature.

In this case the higher the combustion gas temperature at the initial stage of piston displacement and the lower the combustion gas temperature at the point of the piston displacement process termination the higher is the value of J.

The more homogeneous is the burning fuel mixture and the lower is the charge combustion volume the higher is the burning charge temperature. Both of these conditions will be fulfilled if initially this stirred charge mixture is injected at high velocity into the confined combustion space.

Meeting the other high efficiency condition, i.e., the achievement of the lowest temperature possible at the termination point involves the highest possible combustion gases expansion volume, i.e., the greatest possible increase in the actual displacement volume of the Type 2 cylinders.

Such an increase in the Type 2 cylinder volume can be attained either by increasing the toroidal cylinder length or by increasing the cylinder cross-section.

The cylinder length can be achieved through incrementing the rotor diameter which in combination with the cylinder housing forms a toroidal cylinder while the increase in the cylinder cross-section can be achieved by increasing either the width of the height of a cylinder starting from the end of the charge accumulation section.

The previously identified coupled cylinder engine features a simple engine design with two equal volume and size cylinders thus allowing the ready to ignite fuel charge to transfer sideways from one cylinder to another, i.e., from one parallel path to another.

In engines with different diameter cylinders, such sideways charge propagation path bias is augmented with the radial path deviation. Reduction of the total transfer channel length is another prerequisite for a device design optimization.

Other applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:

FIG. 1 is a schematic view of an engine according to a first embodiment of the invention;

FIG. 2 is a schematic representation featuring engine cylinder cross-sectional views with an interconnecting charge transfer path;

FIG. 3 is a schematic representation of the transfer path opening sequence;

FIG. 4 is a transverse cross-sectional view of the engine;

FIG. 5 is a longitudinal cross-sectional view showing a spacer ring including an arciform groove;

FIGS. 6A and 6B are schematic cross-sectional views showing a Type 1 cylinder and Type 2 cylinder respectively of a second embodiment of the invention;

FIG. 7 is a schematic cross-sectional view of the second embodiment of the invention;

FIG. 8 is a cross-sectional view of the second embodiment of the invention with the engine in a work performance position;

FIG. 9 is a cross-sectional view of the second embodiment of the invention showing the interconnecting charge transfer path ready to ignite fuel charge transfer position;

FIG. 10 is a schematic cross-sectional view of a third embodiment of the invention;

FIG. 11 is a cross-sectional view of the third embodiment of the invention showing the interconnecting charge transfer passage;

FIG. 12 is a schematic cross-sectional view showing a fourth embodiment of the invention; and

FIG. 13 is a cross-sectional view of the fourth embodiment of the invention showing the interconnecting transfer passage.

DETAILED DESCRIPTION

The first embodiment of the invention seen in FIGS. 1-6 includes a housing structure 10 defining a toroidal volume including first and second housing sections 12 and 14 and a rotor structure 16 mounted for rotation in the housing structure and including first and second rotor members 18 and 20 respectively coacting with the first and second housing sections to define first and second toroidal cylinders 22 and 24.

Rotor 18 has a generally cylindrical configuration and includes a pair of diametrically opposed lobe portions 26.

The engine further includes a pair of diametrically opposed reciprocally moveable partitions or walls 28 which are mounted in radially outwardly projecting portions 12 a of housing section 12 and are spring biased radially inwardly into engagement with rotor member 18 by compression springs 30.

Each lobe portion 26 includes, in circumferential sequence, a entry portion 26 a, a dwell portion 26 b and a terminal portion 26 c in sealing engagement with the inner periphery 12 b of housing section 12.

Rotor member 20 has a generally cylindrical configuration. A pair of diametrically opposed reciprocally moveable partitions or walls 32 are mounted in rotor member 20 and are spring biased radially outwardly into engagement with the inner periphery 14 a of housing section 14 by compression springs 34.

A pair of diametrically opposed lobe portions 36 is provided on the inner periphery 14 a of housing 14. Each lobe portion 36 includes, in circumferential sequence, an entry portion 36 a, a dwell portion 36 b, and a terminal portion 36 c. The engine further includes intake manifolds 40, inlet ports 42 in the cylinder 22, ignition devices 44 communicating with the cylinder 24, exhaust ports 46 exiting cylinder 24, exhaust manifolds 48 and transfer passages 50.

Each transfer passage 50 is a compound passage establishing communication between cylinder 22 and cylinder 24 only for the period of fuel charge passage. Each passage 50 includes a passage 52 opening in the radially inner end 28 a of wall 28 in exposure to cylinder 22; a passage 54 in housing section 12; an arcuate slot or groove 56 in a partition 58 positioned between cylinder housing sections 12 and 14; a transfer passage 60 in rotor member 20; and a passage 62 in wall 32 opening in cylinder 24. It will be seen when these passages are in alignment, as seen in FIG. 2, the passage is completed between cylinder 22 and cylinder 24. It will be seen that a passage 50 is provided at two diametrically opposed locations within the engine for selective communication between cylinder 22 and 24 at diametrically opposed locations.

As will be apparent, the engine seen in FIGS. 1-6 is arranged with diametrically opposed operating components so that two intake/compression strokes are performed in cylinder 22 and two expansion/exhaust strokes are performed in cylinder 24 for each rotation of the rotor.

Operation

The operation of the engine of FIGS. 1-6 will be described with respect to one set of operating components of the engine and it will be understood that similar operations are simultaneously occurring at the diametrically opposed set of operating components as the engine undergoes two intake/compression and two ignition/exhaust strokes for each rotation of the rotor.

The operation of the engine will be described beginning with the component positions seen in FIG. 1. In FIG. 1 the wall 28 has been moved radially outwardly by the entry portion 26 a of the lobe 26 to a position in which the passage 52 is in alignment with the passage 54 in housing section 10 and in communication with arcuate groove 56 and the wall 32 is positioned on the dwell portion 36 b of the lobe 36 on the inner periphery of housing section 14 with passage 62 in communication with the opposite end of groove 56 whereby to establish communication between cylinders 22 and 24 to begin the charge transfer process from cylinder 22 to 24. It will be understood that prior to arrival at the positions seen in FIG. 1 the rotor 16 would have moved within the housing 10 in a manner such that each lobe portion 26, acting as a piston, would have moved past a respective intake port 42 and coacted with a respective moveable wall 28 to develop a compressed fuel charge and, upon arrival in the positions seen in FIG. 1, will coact with the respective moveable wall 28 to establish a transfer passage between the cylinders 20 and 24 and begin the transfer process.

The transfer process continues for the period of time that walls 28 move along dwell portions 26 b and walls 32 move along dwell portions 36 b. During this time, the passages 62 in the walls 32 are in communication with and move arcuately along arcuate slots 56 whereafter, upon arrival of the walls 28 at the end of dwell portions 26 b and arrival of walls 32 at the end of dwell portions 36 b, the passages between the cylinders are interrupted by the radially outward movement of walls 28, the radially outer movement of walls 32, and the movement of the port 62 beyond the arcuate groove 56.

After the compressed charges are moved to the cylinder 24, the charges are ignited using ignition devices 44 and the expanding gasses act upon the walls 32 to provide power strokes which terminate in the discharge of the dissipated gasses through the respective exhaust ports 46 for discharge through the respective exhaust manifolds 48. During these power and exhaust strokes in the second cylinder, the first cylinder is undergoing a new intake and compression cycle so that when the rotors again assume the position seen in FIG. 1, new compressed charges are ready for transfer to the cylinder 24 to initiate new power and exhaust strokes in the cylinder 24.

According to an important feature of the invention the cross-sectional area of the void 64 between the lobe portion 26 b and the inner housing periphery 12 b in the FIG. 1 position is identical to the cross-sectional area of the void 66 between the outer periphery 20 a of rotor 20 and lobe dwell portion 36 b with the components in the FIG. 1 position. As a result, the charge volume in the second toroidal cylinder during the transfer operation is progressively increased by an amount corresponding to the progressive decrease in the charge volume in the toroidal cylinder 22. Note that in order to maintain an equal cross-sectional volume in the void 66 as compared to the void 64, given the increased diameter of the cylinder 24, the radial height of the void 66 is compensatingly less than the radial height of the void 64.

As an example, the dimensions of the various components of the engine may be chosen such that the volume of the second cylinder 24 is twice that of the volume of the first cylinder 22 with the result that, upon performing the work cycle, the volume of combustion gasses will be twice that of the fuel charge initially filling up the internal space of cylinder 22. This makes it possible to significantly reduce the final temperature t of the combustion gasses which, in accordance with the previously described formula J=1−t/T, will result in enhanced efficiency.

The engine efficiency is further improved, again by reference to the formula J=1−t/T, by maximizing the process commencement temperature t which is accomplished according to an important feature of the invention by maintaining a constant charge volume as the charge is transferred from cylinder 22 to cylinder 24.

In considering the operation of the invention it will be understood that in the first cylinder 22 each reciprocal wall acts as a barrier Wall for coaction with a piston constituted by a respective lobe portion 26 c and in the second cylinder 24 each reciprocal wall acts as a piston receiving the expanding energy of the charge in the power stroke and sweeping the exhaust gasses from a previous cycle out of the respective exhaust port.

The second embodiment of the engine seen in FIGS. 7, 8, and 9 is generally similar to the embodiment of FIGS. 1-6 with the exception that in this case the moveable walls associated with the first cylinder as well as the moveable walls associated with the second cylinder are both mounted in their respective housing sections and are biased radially inwardly against the respective rotor members.

Specifically, the engine of FIGS. 7-9 includes a housing having a first section 70 and a second section 72, a rotor 74 coacting with the first housing 70 to form a first cylinder 76 and including a lobe 78, a second rotor member 80, coacting with the second housing section 72 to define the second cylinder 82 and including a lobe 84, a reciprocal wall 86 mounted in the first housing section and a reciprocal wall 88 mounted in the second housing section.

In this case the transfer passage 90 interconnecting cylinders 76 and 82 during the charge transfer process includes an inclined passage 92 connecting the two cylinders passing through mutually fixed parts of both the cylinder housing sections and through a coupling ring 94, a passage 96 in wall 86 opening in the first cylinder, and a passage 98 in the wall 88 opening in the second cylinder. As seen by a comparison of FIG. 8 showing a work performance position of the engine, and FIG. 9, showing a charge transfer position of the engine, the passages 96, 92 and 98 are normally disconnected to preclude interchange of charge between the cylinders.

When the walls 88 and 86 are moved to the dwell portions 84 a and 78 a of the respective coacting rotor lobes, as seen in FIG. 9, the passages 96, 92 and 98 interconnect to form the passage 90 and allow the transfer of the fuel charge from cylinder 76 to cylinder 82 for so long as the walls 86 and 88 are engaging the respective dwell portions of the respective dwell portions of the respective rotor lobes whereafter the passage is interrupted by subsequent movements of the reciprocating walls to the main body portions of the respective rotors as seen in FIG. 8.

The transfer passage arrangement of the FIG. 7-9 embodiment eliminates the arcuate groove 56 in the FIGS. 1-6 embodiment, reduces the transfer path length and volume, decreases the number of intermediate contacts, and enhances the reliability of the transfer operation.

The engine of the FIGS. 10- and 11 embodiment is generally similar to the engine of the FIGS. 1-6 embodiment with exception that transfer passage between the first cylinder and the second cylinder opens in the second cylinder in the cylinder housing rather than in the reciprocal wall of that cylinder.

Specifically, the engine of FIGS. 10 and 11 includes a housing including a first section 100, a second section 102 and a rotor structure including a first rotor member 104 coacting with the first housing section 100 to define the first cylinder 106 and a second rotor member 108 coacting with the second housing section to define the second cylinder 110.

Reciprocal walls 112 are mounted in housing section 100 for coaction with lobes 114 on rotor 104 and reciprocal walls 116 are mounted on housing section 108 for coaction with lobes 118 on the inner periphery 102 a of housing section 102.

The transfer passage 120 in this case includes a passage 122 in reciprocating wall 112 opening in the cylinder 106, a passage 124 in a central housing partition 126 and a passage 127 opening in a lobe 118 on the inner periphery of hosing section 102 through a series of windows 128.

The ready to ignite fuel charge transfer is initiated at the instant when the entry portion 114 a of lobe 114 lifts the reciprocal wall 112 up onto the lobe dwell portion 114 b. Simultaneously the reciprocal wall 116 moves onto the dwell portion 118 a of lobe 118 whereupon the ready to ignite fuel charge, its constant volume being maintained, begins to flow into the cylinder 110 through the windows 128. During this transfer, the charge is ignited and the combustion process begins. The transfer of the ready to ignite fuel charge is completed when the reciprocal wall 112 travels beyond the dwell portion 114 b of the lobe 114 and is shifted outwardly by the lobe portion 114 c, thus interrupting the transfer passage between the first and second cylinders.

As compared to the engines of the FIGS. 1-6 and 7-9 embodiments, the engine of the FIGS. 10 and 11 embodiment has the lowest number of contact-points between the elements of the ready to ignite charge transfer passage and the shortest transfer passage length.

The engine of the FIGS. 12 and 13 embodiment is similar to the engine of the FIGS. 1-6, 7-9 and 11-12 embodiments with the exception that the moveable walls in this embodiment are mounted for pivotal rather than reciprocal movement.

A reciprocal wall or partition has to be open to the outside atmosphere to avoid pumping of the charge into the compartment. This requires a tight sealing of the wall within the compartment. Further, pressure differences generated between the two faces of wall will force it toward the compartment wall and impede its slide. Further the spring that forces the wall toward the rotor is elongated during the work phase when the partition is outside its compartment and seals the cylinder. Force applied by the spring on the wall at this time is smaller than at the idle phase when the wall is shifted into the compartment to allow the pistons passage. Further the wall has to be light and durable. All of these disadvantages are overcome by replacing the reciprocal wall of the previous embodiments with the pivotally mounted wall seen in the FIGS. 12 and 13 embodiment.

The first cylinder as seen in FIG. 12 includes a housing section 130 and a rotor 132 coacting with the housing section to define a first cylinder 134 and having a lobe 136. The engine further includes pivotal wall 138 mounted on the inner periphery of housing section 130 by a pin 140 for pivotal movement about an axis 142. A bias pin 144 is mounted in housing 130 and includes a roll 146 on its inboard end received in a cavity 138 a in the wall 138. Pin 144 is biased radially inwardly by a compression spring 148 whereby to bias the wall 138 pivotally inwardly to press the free end 138 b of the wall against the periphery 132 a of the rotor. A groove 150 is machined into the inner periphery of housing 130 to accommodate wall 138 in its outwardly pivoted position. The back face 138 c of the wall has a special profile designed to reduce the relative change in the length of the spring 148 (and therefore changes in the force that the spring applies) between the fully open and fully closed positions. Specifically, the partition is thick in the open state and thin in the closed state.

The charge transfer passage 152 passes along the pivotal axis 142 of the wall 138. The passage 152 has the form of a pipe with intake apertures 154 opening in the first cylinder and outlet apertures 156 opening in the second cylinder. The rotating wall rotates about the charge transfer passage and includes apertures 158 that align with apertures 154 during the charge transfer time only and seal with respect to the apertures 154 during the rest of the cycle.

The invention engine will be seen to provide many important advantages for a coupled cylinder rotary type engine.

Specifically, by providing a different configuration for the first and second cylinders the overall efficiency of the engine is improved. Yet more specifically, the process commencement temperature T is maximized by maintaining a constant charge volume during the transfer process and the process termination temperature t is minimized by providing a larger volume for the second cylinder as compared to the first cylinder. Further, the efficiency of the charge transfer process between the first and second cylinders is optimized by keeping the transfer path open only for so long as the actual charge is being transferred and by providing total isolation of gaseous combustion products from the consecutive incoming charges. Overall, by providing different design and dimensional characteristics for the first and second cylinders, the operational aspects of each cylinder may be optimized to provide an optimized overall engine efficiency.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law. 

1-30. (canceled)
 31. A rotary internal combustion engine including a housing structure defining a toroidal volume and including first and second housing sections, and a rotor structure mounted for rotation in the housing structure and including first and second rotor members respectively coacting with the first and second housing sections to define first and second toroidal cylinders, intake and compression strokes being performed in the first toroidal cylinder and the resultant compressed charge being thereafter transferred by a transfer mechanism to the second toroidal cylinder where combustion occurs and expansion and exhaust strokes are performed, characterized in that: (a) the second toroidal cylinder has a larger volume than the first toroidal cylinder; and (b) the transfer mechanism is operative to maintain the volume of the charge substantially constant during the transfer operation irrespective of the larger volume of the second toroidal cylinder as compared to the first toroidal cylinder.
 32. A rotary internal combustion engine according to claim 31, wherein the engine further includes a moveable wall coacting with a first lobe on the first rotor member or the first housing section to define therebetween, during the transfer operation, a charge volume of a predetermined cross sectional area and a second moveable wall coacting with a second lobe on the second rotor member or the second housing structure to define therebetween, during the transfer operation, a charge volume having the predetermined cross sectional areas the first moveable wall and first lobe converging during the transfer operation and the second moveable wall and the second lobe diverging during the transfer operation so that the charge volume entering the second toroidal cylinder during the transfer operation equals the charge volume leaving the first toroidal cylinder.
 33. A rotary internal combustion engine according to claim 31 wherein the engine further includes a moveable wall positioned in the first toroidal cylinder and operative to form a barrier wall in the first toroidal cylinder for coaction with a lobe on the first rotor member or on the first housing section to define a void volume therebetween in the first toroidal cylinder.
 34. A rotary internal combustion engine according to claim 31, wherein the moveable wall is further operative at a selected moveable position thereof to form the entry portion of a transfer passage between the first and second toroidal cylinders.
 35. A rotary internal combustion engine according to claim 31, wherein: the moveable wall is mounted on the first housing section and is biased inwardly into the first toroidal cylinder against the first rotor member; and the lobe is formed on the first rotor member.
 36. A rotary internal combustion engine according to claim 31, wherein the lobe, in circumferential sequence, includes an entry portion operative to move the moveable wall actuation portion operative to move the moveable wall outwardly to its selected moveable position, whereby to initiate the charge transfer, a dwell portion whereby to maintain the moveable wall in the selected moveable position for a predetermined dwell time, and a terminal portion in sealing engagement with an inner periphery of the first housing section and operative to move the moveable wall outwardly to a position in which the transfer passage is interrupted, whereby to terminate transfer of the charge to the second toroidal cylinder.
 37. A rotary internal combustion engine including a housing structure defining a toroidal volume and including first and second housing sections, and a rotor structure mounted for rotation in the housing structure and including first and second rotor members respectively coacting with the first and second housing sections to define first and second toroidal cylinders, intake and compression strokes being performed in the first toroidal cylinder and the resultant compressed charge being thereafter transferred by a transfer mechanism to the second toroidal cylinder where combustion occurs and expansion and exhaust strokes are performed, characterized in that the first and second cylinders have disparate configurations.
 38. A rotary internal combustion engine according to claim 37, wherein the second toroidal cylinder has a larger volume than the first toroidal cylinder.
 39. A rotary internal combustion engine according to claim 37, wherein the transfer mechanism is operative during the transfer operation to progressively increase the charge volume in the second toroidal cylinder by an amount corresponding to the progressive decrease in the charge volume in the first toroidal cylinder.
 40. A rotary internal combustion engine according to claim 38, wherein the larger volume is achieved by increasing the cross sectional area of the second toroidal cylinder as compared to the first toroidal cylinder.
 41. A rotary internal combustion engine according to claim 38, wherein the larger volume is achieved by increasing the diameter of the second rotor member as compared to the first rotor member.
 42. A rotary internal combustion engine according to claim 38, wherein the larger volume is achieved by increasing the diameter and the cross sectional area of the second rotor member as compared to the first rotor member.
 43. A rotary internal combustion engine including a housing structure defining a toroidal volume and including first and second housing sections, a rotor structure mounted for rotation in the housing structure and including first and second rotor members respectively coacting with first and second housing sections to define first and second toroidal cylinders, intake and compression strokes being performed in the first toroidal cylinder and the resultant compressed charge being thereafter transferred by a transfer mechanism through a transfer passage to the second toroidal cylinder where combustion occurs and expansion and exhaust strokes are performed, characterized in that the transfer mechanism is operative to maintain the volume of the charge substantially constant during the transfer operation.
 44. A rotary internal combustion engine according to claim 43, wherein the engine further includes a moveable wall positioned in the first toroidal cylinder and operative to form a barrier wall in the first toroidal cylinder for coaction with a lobe on the first rotor member or on the first housing section to define a void volume therebetween in the first toroidal cylinder and a second moveable wall positioned in the second toroidal cylinder and operative to form a barrier wall in the second toroidal cylinder for coaction with a second lobe on the second rotor member or on an inner periphery of the second housing section to define therebetween a void volume in the second toroidal cylinder; the first moveable wall is held in its selected moveable position for a predetermined dwell time; and during the predetermined dwell time, the decrease in the void volume in the first toroidal cylinder is compensated by a corresponding increase in the void volume in the second toroidal cylinder so that the charge volume is maintained substantially constant during the transfer operation.
 45. A rotary internal combustion engine according to claim 44, wherein the first moveable wall is mounted in the first housing section; the second moveable wall is mounted in the second rotor member; and the transfer passage includes a passage in the first moveable wall opening in the first toroidal cylinder and a passage in the second housing section opening in the second toroidal cylinder.
 46. A rotary internal combustion engine according to claim 44, wherein the moveable wall is mounted on the first housing section and is biased inwardly into the first toroidal cylinder against the first rotor member; and the lobe is formed on the first rotor member.
 47. A rotary internal combustion engine according to claim 46, wherein the lobe, in circumferential sequence, includes an entry portion operative to move the moveable wall actuation portion operative to move the moveable wall outwardly to its selected moveable position, whereby to initiate the charge transfer; a dwell portion whereby to maintain the moveable wall in the selected moveable position for a predetermined dwell time; and a terminal portion in sealing engagement with an inner periphery of the first housing section and operative to move the moveable wall outwardly to a position in which the transfer passage is interrupted, whereby to terminate transfer of the charge to the second toroidal cylinder.
 48. A rotary internal combustion engine according to claim 44, wherein one of the moveable walls is mounted in the respective housing section and the other moveable wall is mounted in the respective rotor member; and the transfer passage includes a passage in the first rotor member opening in the first toroidal cylinder, a passage in the second rotor member opening in the second toroidal cylinder, and an arcuate slot in a central partition separating the first and second housing sections and communicating with the passage in the first rotor member and the passage in the second rotor member during the dwell time.
 49. A rotary internal combustion engine according to claim 44, wherein the moveable wall is mounted for reciprocal movement.
 50. A rotary internal combustion engine according to claim 44, wherein the moveable wall is mounted for pivotal movement. 